 //ts类型:boolean类型
let bool:boolean =true;

//ts类型:number类型
let num:number = 1
num=2

 //ts类型:string
 let str:string = 'abc';
 str = 'efg'

 //ts类型:null和undefined
let a:null =null
let b:undefined = undefined

 //ts类型:bigint(编译的时候可能会报错,因为是es2020的规范,ts默认配置的支持规范小于es2020)
 let num2:bigint = 1n

 //ts类型:symbol
 let sy1:symbol = Symbol()